Can Grapher display date/time labels for non-standard date numbers in the worksheet?

Grapher can create a graph with an axis displaying date/time labels when the data contains numeric values.


There are two major different types of numbers that are stored in worksheets: standard sequential values and non-standard sequential values. Standard sequential values are defined by spreadsheet programs as starting at a certain date and having a certain increment.


A non-standard numeric date is similar to the standard numeric dates, but in these situations, the starting value and increment is determined by the user. So, the value 1 can be any date/time. The increment can be any time interval. So, the value 2 can refer to the next day, like standard serial date numbers; or it can refer to the next second, next year, or a different increment entirely. Some recording devices will record in this manner. This requires additional steps in Grapher to display the dates.

Let's assume that the value 1 is January 1, 2012. Let's further assume that the data should be collected every three weeks. So, the value 2 is January 22, 2012; the value 3 is February 12, 2012; and so on. Our data set may now look like:

non-standard numeric dates
The dates in the left column are in
custom numeric format. Grapher will
set the axis to numeric when creating the graph.


To create a graph from this data, click the Graphs | Create | Basic | Line Plot command. Select the data file and click Open. The X axis will be in numeric format.

non-standard number axis
The X axis is automatically displayed with numbers instead of dates.


After the graph is created, the axis can be converted to dates. To convert the numbers to dates:

  1. Click on the X Axis 1 in the Object Manager to select it.
  2. In the Property Manager, click on the Tick Labels tab.
  3. In the Major Label Text section, set the Label source to Date/time.
  4. Click the Set button next to Date/time settings.
  5. In the Date/Time Labels dialog:
    1. Set the Axis value to 1.
    2. Set the Date to 1/1/2012.
    3. Set the Time to 12:00:00 AM.
    4. Set the Axis increment to 0.0476190. This is the fraction of 1 taken by one day, using the numbering scheme defined above.
    5. Set the Corresponding time increment to Day.
    6. Click the Set date/time format button and set the Language (Country) and Predefined date/time formats to the desired format, such as English (Unites States) - [$409] and MMM. If a predefined format is not listed, you can type the desired format in the Date/Time fomat (edit to change) box. Click OK.
    7. Click OK.
  6. Do not check the box next to the Use date/time format option. This box should remain unchecked.


The axis converts the numbers to dates using the non-standard numbering scheme defined in the data. The axis tick label format must be set in the Format option in the Date/Time Labels dialog. The setting in the Major Labels section of the Property Manager will not have an effect on the axis because the axis is using the non-standard numbers, not date/time formatting.

non-standard number axis dates
The X axis is changed to display with date/time values.


The axis tick mark spacing can be set on the Tick Marks tab of the Property Manager, using the numeric spacing, not the date/time spacing. To change the tick mark spacing:

  1. Click on the X Axis 1 in the Object Manager to select it.
  2. In the Property Manager, click on the Tick Marks tab.
  3. Highlight the value next to Spacing and type the desired value. A month in this situation is approximately equal to 1.531746. So, type 1.531746 and press ENTER on the keyboard to make the Spacing change. This sets the tick marks based on a numeric interval.


Updated September 30, 2016

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